Character comedy usually requires the establishment of a consistent, well-defined character – a boorish pub landlord, say, or foot-in-mouth TV presenter. Nick Mohammed's alter ego Mr Swallow is one of the most vivid comedy personae doing the rounds, even though it has seldom been clear precisely who he is, or what (if anything) he is parodying. That is a testament to the strength of Mohammed's bizarre characterisation: the colossally self-absorbed Swallow can be transposed to any predicament, and he'll still be wittering on, getting excitable and imposing himself where he's not wanted.

At this year's fringe, he stars in his own musical version of Dracula, and the result is a fine example of the "play wot I wrote", bad-theatre genre. Mohammed has clearly made an effort to create an almost-real faux show, replete with choreography, on-stage band, believable songs ("I'm way more famous than Jekyll," sings Dracula, "With nothing so creepy to Hyde") and even moments when the script is played straight.

That gives Mohammed/Swallow something to undermine – and he does so very amusingly. The conceit is that this is a final dress rehearsal, but Swallow keeps interrupting with another quibble, improvising a new character at will (here a Scouse ticket inspector at a ferry terminal), or taking umbrage that Van Helsing has more stage time or Jonathan Harker has more bars in his song. He's northern, shrill and possesses the naive insensitivity of an overgrown child, and the show just can't get around him. "Oh, God, will you stop that now, Jonathan," he trills when Harker staves him off with garlic: "We're not bruschettas!"

The story is hastily dispatched, and the format is limber enough to accommodate an all-singing, all-dancing break for Chinese takeaway. There's nothing more to this than knockabout fun, but it's lovingly crafted and has a generous sense of cheer in the Morecambe and Wise manner.